Establishment of indirect competitive enzyme linked immunosorbent assay for the detection of platycodin D in Radix Platycodonis

Abstract

Platycodin D (PD) has been used as the quality control marker of Radix Platycodonis for its high content and various pharmacological properties. In this study, a specific polyclonal antibody against PD (PD–pAb) was developed, and PD–pAb-based indirect competitive enzyme-linked immunosorbent assay (icELISA) was established for the detection of PD in Radix Platycodonis. The 50% inhibition concentration (IC50) of PD was 2.70 μg/mL and the linearity range for PD was from 0.064 μg/mL to 100 μg/mL. No cross reactivity with PD–pAb was found in five PD analogs except for PD2 (0.93%). The average recovery of PD by icELISA was 97.14% (RSD = 1.17%). There was a good correlation (r = 0.9654) between the PD contents in Radix Platycodonis detected by icELISA and high performance liquid chromatography (HPLC). Taken together, the established icELISA might be a sensitive, specific, simple, cheap and high-throughput method for determining the contents of PD in Radix Platycodonis.